Printing plates made using silver halide sensortype light-sensitive polymerizable materials have been proposed, as described in U.S. Pat. Nos. 3,687,667; 3,697,275; 3,746,542; 3,756,818; 3,756,820; 3,767,400; 3,782,943; 3,782,944; 3,790,378; and 3,874,947 (all Hayakawa et al). These patents disclose situations wherein an ethylenically-unsaturated compound is present in a processing solution or, if it is in the light sensitive material, in the same layer as the silver halide. In each of the references, polymerization of the vinyl compound is achieved by reducing the exposed silver halide in the presence of the compound.
When the silver halide emulsion and the ethylenically-unsaturated compound are in the same layer of a printing plate precursor, there are typically disadvantages. For instance, the thickness of the polymerizing layer is typically thicker because it must additionally contain silver halide material and binder colloid as well as the polymerizable material. Another disadvantage is that because the film typically swells substantially as developer solution penetrates to permit development of the silver halide, the resolution of the resultant printing image may be limited. Furthermore, because a hydrophilic binder must typically be incorporated in the emulsion to aid in dispersing the hydrophilic silver halide throughout the emulsion, the inking characteristics and printing durability of the resultant printing plates is typically inferior when using the polymer images formed therefrom as relief printing plates.
U.S. Pat. No. 3,245,793 (Smith) discloses a process for forming images wherein a developed silver halide image is used as a mask for imagewise irradiation of a layer containing a photopolymerizable non-gaseous ethylenically-unsaturated compound. U.S. Pat. Nos. 4,268,609 and 4,299,912 (both Shiba et al.) disclose similar mask techniques for formation of a printing image via photopolymerization.
U.S. Pat. No. 4,335,197 (Chambers et al.) discloses a method for producing a photopolymer image wherein a photosensitive element comprising a substrate coated with a photosensitive layer containing dispersed silver halide particles in operative association with a continuous film-forming phase of a defined polymeric coupler is used.
U.S. Pat. No. 4,547,450 (Maeda et al.) discloses a multilayer image-forming element in which a silver halide photographic emulsion and a polymerizable ethylenically-unsaturated compound are contained in adjacent layers. According to the reference, the polymerization reaction is initiated by an oxidized radical of a reducing agent that reduces the silver halide latent image.
U.S. Pat. No. 4,557,997 (Iwasaki et al.) discloses photopolymerizable compositions comprising silver halide, high molecular binder, and vinyl monomer. The silver halide is used as a photoinitiator.